OMAHA, Neb. -- When they first crossed paths before a pre-Olympic trials press conference a little over a week ago, Michael Phelps had a bushy moustache and Ryan Lochte a lime green leather backpack. Their rivalry had been built up as the next big thing in swimming, with Lochte peddling the idea that it could be the biggest story in sports.

It seemed sort of laughable at the time, a pair of swimmers outdueling the likes of Yankees-Red Sox, Auburn-Alabama or Bears-Packers. But after four events and a week of head-to-head duels, it's not that funny anymore. In fact, if there's anything we learned this week, it's that the two 27-year-olds have every intention of putting on one heck of a show later this month in London.

Of the four events in which the two swimmers butted heads this week, Phelps won three -- the 200-meter individual medley, 200 freestyle and 100 butterfly -- while Lochte took the 400 IM. But Phelps' combined margin of victory was a mere three-tenths of a second. In no race was the margin less than a second, and Lochte's winning margin of .83 seconds in the 400 IM was the largest. Of the 16 50-meter splits the two rivals swam in finals, Phelps was faster in eight of them, Lochte in seven, and there was one tie.

What does that mean? These guys are close. Really close. And London should be incredible. Here are five other things we learned this week.

Ryan Lochte and Michael Phelps went head-to-head in four events at the U.S. Olympic swimming trials. Al Bello/Getty Images

1. These guys love to race against each other ... um, really love it

If there was any doubt as to how much Phelps wants to beat Lochte and Lochte wants to beat Phelps, all you had to do was look at the final times in Saturday night's 200 IM. In a race in which the top two finishers qualified for London, Phelps and Lochte demolished third-place finisher Conor Dwyer by more than four seconds. Why is that important? Both swimmers had another event that night, and neither would take his foot off the gas and concede second place to his rival. In the grand scheme of things, did first place mater? Not really. Yet neither of them wanted to lose. All week long, Phelps and Lochte repeated how much they hate losing to each other, with Phelps admitting on multiple occasions he has been using Lochte's confidence as motivation. You have to wonder if all the hard work Lochte has been putting in will only serve as further incentive for Phelps.

When coach Bob Bowman added the 400 IM to Phelps' Olympic trials program in March, it sealed the fact his pupil could potentially swim in eight events in London, again. But Phelps didn't even make the connection until about six weeks later, when he was in the middle of a training session. He had a "eureka" moment, popping his head up from the water and saying to Bowman that if he does the 400, it will be the same thing he did in Beijing in 2008.

"And I was like, 'Yeah, you weren't clued in on that yet?'" Bowman said. "'That's why I like when you show up at the pool.'"

But a day after Phelps finished his trials schedule, Bowman changed the plan, announcing via Twitter on Monday that Phelps will remove the 200 freestyle from his London slate:

@MichaelPhelps will be removing the individual 200 freestyle from his Olympic program. This will give him a full slate of 7 events. This change will allow him to focus more energy on relays for Team USA.

Despite the change, Phelps can still make history this summer. He needs just three medals to become the most decorated Olympian of all time and could be the first swimmer to win the same individual event three times. London will not just be a retirement tour.

3. Lochte has an interesting sense of 'fun'

It's no secret Lochte is wired a bit differently. Coach Gregg Troy and trainers at the University of Florida are always trying to come up with twists and tricks to keep Lochte motivated and focused in his training. This time around, it was refusing to scratch the 100 butterfly, which led to Lochte's grueling triple Saturday night -- the 200 backstroke, 200 IM finals and 100 fly semifinal.

Though Lochte won only one of the races, Troy called it one of Lochte's greatest performances of his career. As proof, Troy pointed out that Phelps only beat a tired Lochte by nine-hundredths of a second in the 200 IM. At the end of the night, an exhausted Lochte could barely walk. So why did he do it?

"It was fun," he said. "Something I've never done before. I just wanted to try something new and have fun."

Lochte won't have similar fun in London. By finishing third in the 100 fly Sunday night, he failed to qualify for the U.S. team in the event.

Ryan Lochte and Michael Phelps will face off against each other in the two individual medleys at the London Olympics. Al Bello/Getty Images

4. Phelps is growing up

Those close to Phelps might not agree, but several people within USA Swimming noted this week that the biggest star in their sport appears to be maturing. Maybe it's because of the sentimental pull, knowing his next meet will likely be his last. Or maybe he's gaining perspective on his career -- and life -- as he reaches his late 20s. Whatever the reason, the behind-the-scenes word is Phelps took on much more of a leadership role this week, cheering on and encouraging other swimmers and being more approachable and available. It will be interesting to see if Phelps' peers elect him one of the team's captains for the first time.

5. The best is yet to come

When asked what he has learned this week about the two biggest stars in his sport, NBC swimming analyst Rowdy Gaines laughed. "I don't think we've learned anything," he said. "Everyone else comes out here and treats this like their Super Bowl. For these two guys, it was like a regular-season game."

Gaines said it makes sense because that was the level of effort Phelps and Lochte needed to make the team. In fact, Bowman said this week his swimmer was about "80 percent" where he thought he would be in London. And Lochte noted Sunday he was not fully rested for this meet but would be fully tapered for the Games. He also referred to the trials as a training meet, suggesting there is more to come.

The two swimmers will spend the next three weeks fine-tuning everything from their turns to the way they position their hands in the water, and they will do it while training together. It should all lead to one of the biggest shows in this summer's Games.

"I think they are both capable of so much more and there's no reason to think they're going to let us down," Gaines said. "Every race coming down to a hundredth of a second with those two guys going 1-2. There's never been anything like it in the sport."